content: /* ===========================================================
   * JFreeChart : a free chart library for the Java(tm) platform
   * ===========================================================
   *
   * (C) Copyright 2000-2014, by Object Refinery Limited and Contributors.
   *
   * Project Info:  http://www.jfree.org/jfreechart/index.html
   *
   * This library is free software; you can redistribute it and/or modify it
   * under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation; either version 2.1 of the License, or
   * (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
   * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
   * License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
   * USA.
   *
   * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
   * Other names may be trademarks of their respective owners.]
   *
   * ----------------------
   * RegularTimePeriod.java
   * ----------------------
   * (C) Copyright 2001-2008, by Object Refinery Limited.
   *
   * Original Author:  David Gilbert (for Object Refinery Limited);
   * Contributor(s):   -;
   *
   * Changes
   * -------
   * 11-Oct-2001 : Version 1 (DG);
   * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to
   *               evaluate with reference to a particular time zone (DG);
   * 29-May-2002 : Implemented MonthConstants interface, so that these constants
   *               are conveniently available (DG);
   * 10-Sep-2002 : Added getSerialIndex() method (DG);
   * 10-Jan-2003 : Renamed TimePeriod --> RegularTimePeriod (DG);
   * 13-Mar-2003 : Moved to com.jrefinery.data.time package (DG);
   * 29-Apr-2004 : Changed getMiddleMillisecond() methods to fix bug 943985 (DG);
   * 25-Nov-2004 : Added utility methods (DG);
   * ------------- JFREECHART 1.0.x ---------------------------------------------
   * 06-Oct-2006 : Deprecated the WORKING_CALENDAR field and several methods,
   *               added new peg() method (DG);
   * 16-Sep-2008 : Deprecated DEFAULT_TIME_ZONE (DG);
   * 23-Feb-2014 : Added getMillisecond() method (DG);
   *
   */
  
  package org.jfree.data.time;
  
  import java.lang.reflect.Constructor;
  import java.lang.reflect.InvocationTargetException;
  import java.util.Calendar;
  import java.util.Date;
  import java.util.Locale;
  import java.util.TimeZone;
  
  /**
   * An abstract class representing a unit of time.  Convenient methods are
   * provided for calculating the next and previous time periods.  Conversion
   * methods are defined that return the first and last milliseconds of the time
   * period.  The results from these methods are timezone dependent.
   * <P>
   * This class is immutable, and all subclasses should be immutable also.
   */
  public abstract class RegularTimePeriod implements TimePeriod, 
          Comparable<TimePeriod> {
  
      /**
       * Creates a time period that includes the specified millisecond, assuming
       * the given time zone.
       *
       * @param c  the time period class.
       * @param millisecond  the time.
       * @param zone  the time zone.
       * @param locale  the locale.
       *
       * @return The time period.
       */
      public static RegularTimePeriod createInstance(Class c, Date millisecond,
                  TimeZone zone, Locale locale) {
          RegularTimePeriod result = null;
          try {
              Constructor constructor = c.getDeclaredConstructor(
                      new Class[] {Date.class, TimeZone.class, Locale.class});
              result = (RegularTimePeriod) constructor.newInstance(
                      millisecond, zone, locale);
          }
          catch (NoSuchMethodException e) {
              // do nothing, so null is returned
          }
          catch (IllegalAccessException e) {
              // do nothing, so null is returned
          }
          catch (InvocationTargetException e) {
              // do nothing, so null is returned
          }
          catch (InstantiationException e) {
              // do nothing, so null is returned
          }
          return result;
      }
  
      /**
       * Returns a subclass of {@link RegularTimePeriod} that is smaller than
       * the specified class.
       *
       * @param c  a subclass of {@link RegularTimePeriod}.
       *
       * @return A class.
       */
      public static Class downsize(Class c) {
          if (c.equals(Year.class)) {
              return Quarter.class;
          }
          else if (c.equals(Quarter.class)) {
              return Month.class;
          }
          else if (c.equals(Month.class)) {
              return Day.class;
          }
          else if (c.equals(Day.class)) {
              return Hour.class;
          }
          else if (c.equals(Hour.class)) {
              return Minute.class;
          }
          else if (c.equals(Minute.class)) {
              return Second.class;
          }
          else if (c.equals(Second.class)) {
              return Millisecond.class;
          }
          else {
              return Millisecond.class;
          }
      }
  
      /**
       * Returns the time period preceding this one, or <code>null</code> if some
       * lower limit has been reached.
       *
       * @return The previous time period (possibly <code>null</code>).
       */
      public abstract RegularTimePeriod previous();
  
      /**
       * Returns the time period following this one, or <code>null</code> if some
       * limit has been reached.
       *
       * @return The next time period (possibly <code>null</code>).
       */
      public abstract RegularTimePeriod next();
  
      /**
       * Returns a serial index number for the time unit.
       *
       * @return The serial index number.
       */
      public abstract long getSerialIndex();
  
      //////////////////////////////////////////////////////////////////////////
  
      /**
       * Recalculates the start date/time and end date/time for this time period
       * relative to the supplied calendar (which incorporates a time zone).
       *
       * @param calendar  the calendar (<code>null</code> not permitted).
       *
       * @since 1.0.3
       */
      public abstract void peg(Calendar calendar);
  
      /**
       * Returns the date/time that marks the start of the time period.  This
       * method returns a new <code>Date</code> instance every time it is called.
       *
       * @return The start date/time.
       *
       * @see #getFirstMillisecond()
       */
      @Override
      public Date getStart() {
          return new Date(getFirstMillisecond());
      }
  
      /**
       * Returns the date/time that marks the end of the time period.  This
       * method returns a new <code>Date</code> instance every time it is called.
       *
       * @return The end date/time.
       *
       * @see #getLastMillisecond()
       */
      @Override
      public Date getEnd() {
          return new Date(getLastMillisecond());
      }
  
      /**
       * Returns the first millisecond of the time period.  This will be
       * determined relative to the time zone specified in the constructor, or
       * in the calendar instance passed in the most recent call to the
       * {@link #peg(Calendar)} method.
       *
       * @return The first millisecond of the time period.
       *
       * @see #getLastMillisecond()
       */
      public abstract long getFirstMillisecond();
  
      /**
       * Returns the first millisecond of the time period, evaluated using the
       * supplied calendar (which incorporates a timezone).
       *
       * @param calendar  the calendar (<code>null</code> not permitted).
       *
       * @return The first millisecond of the time period.
       *
       * @throws NullPointerException if <code>calendar,/code> is
       *     </code>null</code>.
       *
       * @see #getLastMillisecond(Calendar)
       */
      public abstract long getFirstMillisecond(Calendar calendar);
  
      /**
       * Returns the last millisecond of the time period.  This will be
       * determined relative to the time zone specified in the constructor, or
       * in the calendar instance passed in the most recent call to the
       * {@link #peg(Calendar)} method.
       *
       * @return The last millisecond of the time period.
       *
       * @see #getFirstMillisecond()
       */
      public abstract long getLastMillisecond();
  
      /**
       * Returns the last millisecond of the time period, evaluated using the
       * supplied calendar (which incorporates a timezone).
       *
       * @param calendar  the calendar (<code>null</code> not permitted).
       *
       * @return The last millisecond of the time period.
       *
       * @see #getFirstMillisecond(Calendar)
       */
      public abstract long getLastMillisecond(Calendar calendar);
  
      /**
       * Returns the millisecond closest to the middle of the time period.
       *
       * @return The middle millisecond.
       */
      public long getMiddleMillisecond() {
          long m1 = getFirstMillisecond();
          long m2 = getLastMillisecond();
          return m1 + (m2 - m1) / 2;
      }
  
      /**
       * Returns the millisecond closest to the middle of the time period,
       * evaluated using the supplied calendar (which incorporates a timezone).
       *
       * @param calendar  the calendar.
       *
       * @return The middle millisecond.
       */
      public long getMiddleMillisecond(Calendar calendar) {
          long m1 = getFirstMillisecond(calendar);
          long m2 = getLastMillisecond(calendar);
          return m1 + (m2 - m1) / 2;
      }
  
      /**
       * Returns the millisecond (relative to the epoch) corresponding to the 
       * specified <code>anchor</code> using the supplied <code>calendar</code> 
       * (which incorporates a time zone).
       * 
       * @param anchor  the anchor (<code>null</code> not permitted).
       * @param calendar  the calendar (<code>null</code> not permitted).
       * 
       * @return Milliseconds since the epoch.
       * 
       * @since 1.0.18
       */
      public long getMillisecond(TimePeriodAnchor anchor, Calendar calendar) {
          if (anchor.equals(TimePeriodAnchor.START)) {
              return getFirstMillisecond(calendar);
          } else if (anchor.equals(TimePeriodAnchor.MIDDLE)) {
              return getMiddleMillisecond(calendar);
          } else if (anchor.equals(TimePeriodAnchor.END)) {
              return getLastMillisecond(calendar);
          } else {
              throw new IllegalStateException("Unrecognised anchor: " + anchor);
          }
      }
      
      /**
       * Returns a string representation of the time period.
       *
       * @return The string.
       */
      @Override
      public String toString() {
          return String.valueOf(getStart());
      }
  
  }
  